Must you send a lone sub against a huge fleet that is blocking the way that is preventing you from bringing a carrier into position (say during NCM) to pick up planes that could potentially survive and need a landing space from some other battle, even though you “know” that you cannot win this battle in any event and that the planes will end up ditching?
Yes in low luck, and yes without. The only hitch here is that you MUST send the sub to make this attack. You cannot win a battle you do not attempt to fight.
I do see what you are saying, that in low luck, there are no “hits and misses” and therefore, since the attack could never be won without immense luck, that it doesn’t meet the summary judgment rule (all attacker hits and all defender misses). But as you also mention, low luck is a tacked-on rule, so we just go back to what it says in the main rulebook; if there is any chance no matter how slight of you winning, you can bring the fighters as long as you make some attempt with at least 1 unit to clear the crucial zone. The sub still meets the test of the rule even though low luck makes its odds go from 1% to 0%.
What if we attack the blocking fleet with a (damaged?) aircraft carrier, alone, which has no combat rating and therefore, can never “inevitably” hit? Maybe this is an even gameyer test of this rule (though we may find some other rule that states that you have to bring at least 1 attacker with attack value into a combat…)
You must be able to win, if you play low luck this becomes a bit of a strange situation indeed.
Low-Luck is a house rule ( like many others ) so if you dont specify anything for this situation it becomes a mather of debate.
Since there should be a non 0 chance, and there is no way a sub will win in low luck you can easy calculate that result, your carrier can never move there.
But if you are attacking with air against some defenders you can also garantee dat your fighters will never survive ( so cannot kill a stack of transports )
Personaly even with low luck i would ignore the low-luck rules during combat moves but you could agrue that since you make use of them during combat-moves you also have to use them if they are not in your favor. So i guess this is something to clarify in advance before starting a game, just like the limitations on where to place your bids.